Electric furnace.



J. M. LOHR & H. W. GILLETT. ELECTRIC FURNACE.

APPLICATION FILED AUG.3I. 1915.

1,1 62,1 79. Patented Nov. 30, 1915.

.fiu/en tars:

UNITED STATES PATENT OFFIOE.

JAMES M. LOHR AND HORACE W. GILLETT, F ITHACA, NEW YORK.

nnnoraro FURNACE.

- Specification of Letters Patent.

Application filed August 31, 1915. Serial No. 48,338. (DEDICAT EZDTO THE PUBLIC.)

To all whom it may concern Be it known that we, JAMES M. LOI-IR and have invented certain new and useful Improvements in Electrical Furnaces, of which the following is a specification.

This application is made under the act of March 3, 1883, c. 143, (U. S. Stat., 22, p. 625) and the invention described hlerei may be used by the Government of the United States, or any of its officers or employees in the prosecution of the work of the United States or by any person in the United States without payment of any royalty thereon.

This invention relates to electric furnaces and more particularly to crucible multiple liftout furnaces which may be used for melting substances such, for example, as brass and other metals or alloys, or for heat treatment thereof.

One object of our invention is to arrange the heating elements in the furnace so that the maximum part of the heat developed will be imparted directly to the substances to be heated.

,Another purpose of our invention is to keep the furnace walls cool to prevent their deterioration and to economize heat and is a plan .view of one form of the invention,

with the furnace covers removed, the electricalconnectlons and certam structural features being diagrammatically or conventionally shown. Fig. 2 is a similar view of a modified furnace of larger capacity.

Referring to Fig. l, the furnace comprises a casing 1 of rectangular or other convenient taining crucibles 26.

angular contour for inclosing a plurality of Patented Nov. 30, 1915.

spaced crucibles 3, 4, 5, 6, of any, preferred shape. Entering centrally through the walls are electrodes 2' which carry the current to the resistors 7, the latter being extended inwardly at right angles to the walls of the casing. Two adjacent resistors 7 are joined in series at their inner ends by a refractory conductor 8 and the remaining pair of'resistors are similarly joined in series by another conductor 8, the two conductors 8 being spaced apart and insulated from each other. The resistors are joined in series with each other and with a source of electrical energy 12 by connectors 9, l0, and 11. This arrangement divides the furnace into four equal heating chambers, each of which is heated from two resistors 7. Since every resistor is wholly between two chambers the heat developed therein will be almost entirely transferred directly to the chambers and their contents. The casing 1 is only indirectly heated and so is at a much lower temperature than in those types of furnaces where the walls are directly heated. This greatly lessens "the heat loss through the walls when the furnace is run continuously, and diminishes the energy lost in repeatedly reheating the walls when the furnace is operated intermittently. The durability of the walls is correspondingly increased.

he size of chamber and size of crucible are so related that there is suflicient space at the sides of the crucible to permit of the latter being readily lifted out or replacedi Referring to Fig.2, the casing '2l'incloses a series of eight equal heating chambers con- These, chambers are separated by resistors 25 extending from the electrodes 23 in the casing-21f to the refractory conductors 24 arranged at the corners of the inner rectangular wall 22;; The resistors 25, electrodes 23 and conductors 24 are connected in series with a source of electric current 27 by means of conductors 28. Thus every chamber is heated directly by two resistors with the same advantages that are obtained in the furnaces'hown in Fig. 1. While any suitable and known resistors may be used,'we have shown, for purposes of illustration, the resistors 7 as granular, and the resistors 25 as being composed of carbon plates. Any desired electrical connections-inay be substituted for the series connection shown, in order to adapt the furnaces to the particular power service that is available. Suitable regulating resistances (not shown) may be used if necessary. The resistors 25 may be regulated in the wellknown way by varying the pressure between the plates thereof.

The form of furnace in F ig. 2 may be adapted to some existing types of fuel-fired furnaces which are arranged about a central stack, the refractory furnace walls being utilized.

Various changes in details of construction and arrangement of parts may be made by one skilled in the art without departing from the spirit and scope of the invention as set forth in the following claims.

We claim 1. An electric furnace including two refractory walls in angular relation, an electric heating element extending inwardly of the furnace from each wall, said elements converging inwardly and being electrically connected at their inner ends.

2. An electric furnace including a plurality of surrounding refractory walls in an 'gularrelation, electric heating elements extending inwardly of the furnace from said ,walls, the elements from adjacent walls converging inwardly of the furnace and being electrically connected in pairs at their inner ends.

3. An electric furnace including a substantially rectangular casing, electric heating elements extending inwardly substantially perpendicularly to said casing, so as to divide the furnace into equal heating chambers, said elements converging inwardly in pairs, the inner ends of each pair being electrically connected by a refractory conductor.

4. An electric furnace comprising a rectangular outer wall, a spaced concentric rectangular inner wall, and a plurality of electric heating elements extending between said walls so as to divide the space between the walls into a plurality of chambers, each of which is heated by two of said elements.

5. An electric furnace comprising a square outer wall, a concentric square inner wall spaced therefrom, refractory electrical conductors at the corners of said inner wall, and resistors connected to sald conductorsand extending therefrom toward the outer wall and at right angles thereto.

JAMES M. LOHR. HORACE W. GILLETT.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. G. 

